Self-styled mistress Karen Marly argues that it can. She is currently involved with four married men who she sees once or twice a month.

She said she makes these men feel better about themselves.

"We've got an awful lot of stresses and strains in our lives. We've got financial problems, we've got work that's on top of us and if you're not feeling great about yourself, your self esteem gets a knock," she explained.

"All of a sudden you start feeling very depressed, very down, very sad about everything and you feel you can't tolerate everything that's going on in your life.

"I am an ego massage for them - it's all about the fact that you are paying attention to someone whose jokes aren't funny at home anymore, whose stories are a little bit dull."

Agony Aunt Anne Atkins disagreed with this and said having an affair is the end of the relationship and therefore can never be justified.

Everybody is capable of cheating.

Karen Marly, self-styled mistress

She also argued that Karen's actions are not considerate of the wife or any children.

"I'm sure your massaging his ego, but what are you doing to her ego - it's a terrible thing to do to another woman," she told her.

"Obviously adultery feels good when you first engage in it, otherwise nobody would do it.

"But the long term effects can be absolutely devastating."

However Karen maintained she was providing a service to married couples - giving their marriage the shakeup it needs.

She said: "They go home a better husband - yes, they are cheating but that's their choice to cheat.

"And all of a sudden he's back to being in his 20s, when he was fabulous and interesting."